Superior Energy Retrieval (SER) allows you to retrieve Energy cards from the Discard pile. This is not the same as playing an Energy card. The question asked if it was possible to play more than the maximum of 1 energy per turn.
Jacob used the SER to get four Water Energies from his Discard pile. Then, he used Blastoise's Deluge to attach those four Energies to Keldeo EX.
So, to answer your question sumwum, under normal circumstances you cannot attach more than one Energy per turn. However, there are totally legal and useable methods that allow you to circumvent this rule through Abilities, moves, and Trainers. SER isn't relevant to the question because its effects do not include applying Energy cards, only adding them to your hand.
It is TOTALLY acceptable to apply more than one Energy card per turn IF you have a card that allows you to. My proof? This was used at a TCG National Championship.